Steam-engine



F. L. 0. WADSWORTH.

STEAM ENGINE.

APPLICAHON HLED 9m12.191s.

F. L. 0. WADSWORTH.

STEAM ENGINE.

APPLICATION FILED Dc.12,191s.

Patented Aug. 3, 1920.

5 SHEETS*SHEET 2.

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F. L. 0. WADSWORTH.

STEAM ENGINE.

APPLICATION FILED 0m12.191s.

Patented Aug. 3, 1920.

s SHEETS-SHEET a.

F. L. o. WADSWURTH.

STEAM ENGINE.

APPLlCATlON FILED 050.12, 191.6- 1,348,256. Patented Aug. 3, 1920.

5 SHEETS-SHEET 4.

UNITED STATES PATENT oFFicE.

FRANK L. 0. WADSWORTH, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO SKINNERENGINE COMPANY, or man, PENNSYLVANIA, A coizoRA'iToN oF PENNSYL- vANIA.

To all ywhom. it may com/eraf Be it known that I, FRANK L. O.WADswoiiTii, a citizen of the. United States residing at Pittsburgh, inthe county of Allegheny and State of Pennsylvania, have invented certainnew and useful Improvements in .Steam-Engines; and I do hereby declarethe following to be a full, clear, and exact description oftheinvention, such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to theaccompanying drawings, and marked thereon, forming part of thisspecification.

This invention relates to steam engines, and has for its object a modeof procedure and an arrangement of mechanism whereby initialcondensation within the cylinder will be substantially reduced.

' I accomplish this object by providing means, controlled by some movingpart o the engine, adapted to convey a portion of the supply of workingsteam into the hollow engine piston, and therefrom back into the workingsteam supply, before it has been admitted into the engine cylinder, bythe end walls of the hollow piston may be raised to and maintained atany desired temperature.

The terms working steam and motor steam as used in this specificationare being used to denote steam synonymous, flowing from a steamgenerator to the valve controlled inlet ports ofthe engine and thence tothe cylinder to impart motion to the piston of the engine, incontra-distinction to jacket steam.

This invention is applicable to all reciprocating steam engines;therefore while the invention is illustrated in the accompany-` ingdrawings as applied to uni-directional flow engines it must not beconstrued as limited-to use with that type of engine.

The features of my invention are hereinafter more fully described andpointed out and are illustrated in the accompanying Figure 1, is alongitudinal vertical section of a portion of an engine cylinderembodying my invention, showing the piston at the end of its rearwardstroke.

Fig. 1a, is a sectional fragmentary view of a modified construction ofthe piston.

Specification ot Letters Patent.

to the letters of reference wherei on the rear end of the cylinderSTEAM-ENGINE.

Patented Aug. 3, 1920.

Application mea December i2', 191e. sriai No. 136,460.

Fig. 2, is a longitudinal vertical section of a portion of an enginecylinder embodying my invention showing the piston at the end of its.forward stroke.

Fig. 3, is an enlarged View of a portion of the tail rod constructionshown in Figs.' 1 and 2 partially in section.

Fig. 4, is an enlarged modification thereof.

Fig. 5,'is a longitudinal vertical section of a portion of an enginecylinder showing lanotherl form of mechanism embodying my invention, thepiston being at the end of its rearward stroke.

v Fig. 6, is a like View thereof, showing the piston at the end of itsforward stroke.

Fig. 7 is a longitudinal vertical section of a portion of an enginecylinder showing another form of mechanism embodying my invention, thepiston being at the end of its rearward stroke.

Fig. 8, is a like view showing the engine lpiston at the end of itsforward stroke.

' the engine piston at the end of its rearward stroke.

Fig. 13, is a like view thereof showing an engine piston at the end ofits forward stroke.

Fig. '14, is a transverse section on the line, z2-.r in Fig. 13.

In these drawings A indicates the engine cylinder having thereon theusual inlet valve seats A and inlet ports a leading from the valve seatsA to the interior of the cylinder A. A2 indicates the hollow c linderhead into which motor steam-from the steam supply of the engine isintroduced for the urpose of heating the inner wall a thereo A3indicates the hollow cylinder head on the front end of the cylinder (seeFigs. 9, 10, 11, 12

and 13). B indicates the hollow piston, and B indicates the piston rodsecured to the hollow piston B.

In Figs. l, 2, 3 and 4 a hollow tail rod C extends rearwardly beyond thehollow piston B, through a stuffing box a2 in the rear head 'A2, theinterior thereof communicating with the cavity the piston by means of anopening C from which a piece of tubing C2 extends downwardly to a pocketb in the wall of the piston B at the lower side thereof. Within vthetail rod C is placed a tube D vwhich is of smaller exterior di; ameterthan the interior diameter of the tail rod C, so that there is .annularpassage between the tube .D andlllttle, interior wall of the tail rod C.

The tube D is maintained in spaced relation to the tail rod C by beinginserted into a longitudinal opening b inthe piston rod B and by a valvehousing D secured in the rear end of the tail rod C and on the rear endof'the tube D.- WVithin this valve housand a chamber e thereinad'acentto the cylinder head A2. The cham er e in the casing Ecommunicates with the interior of the cylinder head A2 by means of .anopening as through the rear wall of said cylinder head. The casin' E isprovided with a duct e2 which leads and bushing ELwhich port opening ispreferably provided with a valve e* for controllin the same.` l

nioperation when the piston B is moved forward by steam admitted intothe inlet portv a to the position thereof shown in Fig. 2, the tail rodC moves forwardly within the casin E and lowers the pressure within thecham er e in said casing until the port opening e3 is uncovered by thetail rod when steam from the interior of the cylinder' head` A2 willflow into the chamber e behind the B, when there is little, if any,movement thereof while the engine-crank (not shown) passes its center.which passes through the port e3 into the chamber e at the end of theforward stroke of the piston B is regulated somewhat by thesize of theport e3, and also by the speed of .the engine; because if the engine isrunning at fullspeed the pause of the, tail rod at the end of theforward stroke of the piston is of shorter duration than when the engineis rom an opening a* in thev rear wall of the cylinder head A2 to a portopening e3 through the wall of the casing Erv C. I also he. quantity ofsteam valve-. e W ich coperates withft e* port running at reduced speed;and in that case the port e3 will be uncovered momentarily, while thelowerin of the pressurer in the chamber e by the orward movement of thetaill rod C will be the same at any speed of the engine. Cn the returnof the from the position thereof shown in ig. 2, to that shown in Fig.1, the steam trapped in the chamber e by thep closing of the portopening e will be forced throu h the valve D2 in the rear end of thetail ro and thence through the tube D into the piston B through theopening C, the port opening Ca in the tail rod being uncovered during alarge portion of the rearward travel of the tail rod and communicatingwith the chamber e inthe casing E so that the continued reciprocation ofthe piston B. and tail rod C will cause a pulsating flow of steam'through the valve D2, piston B, and back into the cylinder'head A3.

It will be noted that during the opera. tion ofthe mechanism abovedescribed, ,when the port opening Ca in the tail rod C moves rearwardlyinto fthe bushing E the* flow of steam from the piston cavity throu hsaid tail rod is stopped, and that lthere ore from the time of theclosing of said port opening C? to the end of the rearward movement ofsaid tail rod linto the chamber e, steam within said chamber e is forcedthroughthe valve D2 and tube D piston B into the 'piston cavity, whilethereis no means by which it can escape therefrom, thereby increasingthe pressure within saidcavity' during the latter `portion of therearwardmovementof 'fthe hollow lpiston B. -Then whenthe piston-B andtail rod C moves forward the pressure in the chamber e is reduced byreason of the removal therefrom of the cubic volumeof that portion ofthe tail rod which extends rearwardly from the port opening e! In Fig. 4I showl a modification of the above described mechanism in vwhich thecheck. valve is removed from the end of the v tail rod and placed in thesteam duct e2 in the casingE, said duct e2 beine` extended to the rearend of the casing E. n this figure, Csindicates the tail rod having atube D4 'which is open, with a bushing d between the Y tube D* and thetail ,rod C5; and inthe duct rear end .of the tail rod C, which occursat the end of the forward stroke of the pistony .ward flowof' steamthrough said duct during the rearwardmovement of the ,tail-rod referablyprovide a re ulating opening e to resist the flow of steam throu h saidport opening." .By means of this mec 125 anism the, steam Iwhichowsthrough the duct e2 and port e to fill the space in the the tail-rod,must, during' the rearward 1h80 o f shown in Fig, 2, to the posltionshown inv Fig. 1'.

t will thus be seen'that applicant has provided mechanism' in whichthere is a chamber of reduced pressure during the forward movement ofthe piston into which the parts.. It will be further understoodV l thatthe advantage of insulatin the central portion. of the piston fromthereof and from vthe c linder exhaust-such steam is admitted at the endof said for-\ ward movement, and the passage through which steam isadmitted to said chamber is provided with a valve e* by means of whichsaid passageway may be restricted as desired, and that during therearward movementof the piston the steam'therein is com-v as has beendescribe in the construction shown in Figs. 1 and 2-can' beutilizedinconnection with 'all of the other constructions disclosed herein, 4aswell as -in connection with such other modifications asfm'ay be readlydevised to embody the principles of my invention'.

In Figs. 5 and'6- a hollow tailf rod F extends rearwardly from thepiston B through a stuffing box a2 inthe rear cylinder head A?, and isprovided Awith a port o ning f adjacent to the rear end thereof. rom theinterior of the hollow piston B an opening b2 communicatesA with theinterior of the pressed sufficiently to force it back into the supply ofmotor steam in the hollow head A?.

The use of heated piston construction is peculiarly advantageous inreducing initial condensation of steam when it first enters' the ends ofthe engine cylinder and comes i be maintained at substantially the sametem- A cooling effect can, however, be minimized by insulating thecentral portion of the piston from the end portions and also byinsulating the central portion of the piston from the portions of thecylinder wall in the neighborhood of the exhaust ports. One of thesimplest means of securing the latter result is to reduce the diameterof the central part of the piston between the piston rings in theAmanner shown in Figs. 1 and 2. This reduction in diameter leaves anarrow annular space between the piston and the wall of the cylinder,which serves not only to insulate the parts and prevent the' directconduction of heat from the piston to the cylinder in the neighborhoodof the exhaust ports, but performs another useful function in thetrapping and retaining of a certain amount of moist, low pressure steamthat acts as a lubricant to the moving surfaces. The insulation of thepiston ends from the central portion of the body of the piston may beeffected where desired, by such a construction of piston as that shownin Fig. la, where the central shell Z of the piston is formed separatelyfrom the ends thereof, which ends are bolted or otherwise secured to theshell Z with an interposed gasket of non-conducting material betweenhollow tail rodF within the tail rod F there is a hollow extension F onthe piston rod B, which communicates with the interior of the piston Bthrou h the duct b3. This hollow extension F o the piston rod B ispreferably of a length equal to the travel of the piston B. Against therear `wall of the cylinder head A2 I lace a casing F2 which covers thetail rod as shown in Fig. 5; and secured in the rear end of the casingF2 there is a tube G which extends forwardly toward the inner end of thecavity in the piston rod extension F the vbore g of the tube Gcommunicating with the duct b3 when the piston is at the end of itsbackward stroke, as shown in Fig. 5; the tube G is also provided with apot ,opening g adjacent to its closedl rear en Within the casingFz'Isecure a bushing F3 adapted-to form a bearing and guide for the tail rodF and prevent the escape of steam around said tail rod. In the upperportion of the casing F2 there is a duct f which communicates with theinterior of the cylinder head A2 through an opening a* in the rear wallthereof, and with a port `opening f2 in the bushing F 3. On the tube'G Isecure a piston G whichl lfits the interior surface of the tail rod F,and is located therein just back of the port openin f2 in the bushingF3, and saidy casing is provided with a duct fs which communicates withthe interior thereof at a point to the rear of the bushing F3, and withthe interiorof the cylinder head A2 through an opening a3 in the rearwall thereof.

In the operation of the mechanism shown in Figs. 5 and 6 steam isadmitted into the cylinder head A2 to'heat the inner wall a thereof andto the inlet port a through the valve seats A to move the piston Bforward, and as it moves forward communication between the tube G andthe duct b3 in the piston B is cut off, which prevents any backward flowof steam from the casing F2 throughthe tube G into the piston B and toreduce the pressure within thetail rod .F v

and piston B,and the piston rod extension F, durin parts; sai reductionof pressure within said parts continuing until the port f in the wall ofthe hollow tail rod F passes the piston G and comes intov coincidencewithv the port f the wall of the plstonrod extension. The

opening in the bushing F 3 during-the short lpause of said piston B atthe end of its forward stroke, thus reducing the pressure. in a seriesof communicating chambers conslst- .ing of the hollow tail rod, hollowpiston, and

hollow'piston` rod extension during the for-4 ward movement-ofsaidparts, into which steam is admitted from the cylinder head A2 at the endof the forward travel of the hol'- low piston B.

The quantity of steam which rushes into the hollow tail rod and hollowpiston during the coincidence of the port f and port f2, 1s 4regulatedsomewhat by the size of said ports and also by the speed of the engine;because if the engine is running at high speed the period of coincidenceof said ports is of shorter duration than when the engine is running atreduced speed, while the piston G and tube G will exhaust the same cubiccontent from the piston B and tail rod F at all speeds during eachreciprocation thereof.

0n the return movement of the engine iston B to the osition thereofshown in ig. 5, the tube and the piston Gforces the steam trapped by theclosing of the port f2 from thetail rod F and piston rod extension Finto the cavity of the piston B wherein it is compressed durin therearward movement 0 the piston until the duct b3 n the piston Bcoincides with the opening in the tube G, which relieves the compressionby permitting the compressed steam to escape from the piston to the rearend of the tube G and thence into the casing F2 from which it can flow`through the duct f3 into the cylinder head A2.

It will therefore be seen that a limited quantity of motor. steam isthus introduced into a series of communicating chambers inclndingthepiston B after-the pressure therein has been reduced, and that as thespeed of the engine increases, the lamount of' raised sufliciently tocause a flow back into the supply of motor steam withinthe cylinderhead.

In Figs. 7 and 8 the piston rod B is provided with an extension H whichextends rearwardly through a stuing box a2 in the.

rear cylinder headl A2 and has therein two the forward movement'of saidducts H and H2, the duct H extending from Athe rear end of the pistonrod exten-` sion forwardly Vto a point adjacent tothe innersurface ofthe front end wall of the,4

engine piston B, -where a lateral opening la, communicates with theinterior of 'the engine piston B; and the rear end of said duct isprovided with a port opening h in other duct H2 extends forwardlyfromthe rear end of the piston rod extension H to a point adjacent tothe inner face of the rear wall of the engine piston B where a lateralopeningy h2 communicates through a short tube ha with the interior ofthe engine pist'on B; said duct H2 being provided with a port opening h4through the wall of said piston rod extension adjacent Ato the rear endthereof. The rear ends of said ducts H and H2 are closed by means ofscrew plugs e.

Secured against the rear face of the cylinder,head A2 is a casin I whichincloses the pistonrod extension and in which .is secured a bushing 'I'which operates as a bearing of the piston rod extension H; the casing Iis provided with a duct 11 which communicates with the interior of thecylinder chamber .J and a valve J opening thereinto, I

from which valve chamber a passage J2 leads into the duct H3. The ductz' is provided with a regulating valve K adapted to restrict the passageof steam therethrough. y

In operation steam is admitted to the hollow head A2 and inlet port a,and as lthe piston B moves forward, the piston rod ex tension H leaves aspace in the casing I in which the pressure is reduced, andwhen 1 theport opening H in the side of the piston rodl extension I-I coincideswith the port opening h5, and the lclvrt opening h4 in the piston rodextensionl comes over the slot h in the bushing I as shown in Fig. 8,said -reduced pressure is communicated through the duct H2 to the cavityin the piston B, and the ports h and h5 being -coincident, steam fromthe duct z' rushes through the duct H into the piston B, and thecontinued reciprocation of said ports draws the steam from the hollowpiston B through the duct H2 into the interior of the casing I, fromwhere it is compressed through the valve J and duct H3 into the cylinderhead, while fresh steam is ad. mitted into the duct H during the periodof coincidence of the ports L and h5 at the end of each `forward strokeof the piston B. In other words the pressure in the cavity of the pistonB is sufhcientlyreduced by reason of the forward movement of the tailcrossing its dead center, it will be obvious l that as" the speed of theengine increases, the pauses at the endsof the strokes of the pistonwill be lessened in duration; while the capacity of the tail rod andcasing I to cause an indrawing of steam into the piston, while remainingthe same for each forward and backwargvement of the piston, will begreatly increased by the increased frequenc of the piston strokes; thelength cf the s ot he permitting a longer period of time for the reducedpressure in the chamber I to exhaust steam from the piston B.

In Figs. 9 and 10 I show another form of mechanism which embodiesmyinvention, in which a sleeve L is secured in the front cylinder headA2 which extends rearwardly into the cylinder, and a short-distance intothe pist'on B, when said piston is at the rear end of its stroke. Inthis case the pist0n4 is provided with semi-spherical end walls, and thefront and rear cylinder heads A2 and A2 have their inner walls aconcaved to fit the contour of said piston end walls. In this manner thepiston can be lengthened for the purpose of embodying the form ofmechanism shown in Fi 9 and 10 without shortening the lengt of thepiston stroke.

The piston B is provided with a logau! dinal cylindrical chamber L',into which the sleeve /L projects, thus leaving an annular space orchamber Z around the piston rod B. Within the cylinder head A3 there isa port openin Z through the wall of the sleeve L.; and also provide aport opening Z2 in the wall of the sleeve L inside of the cylinderadjacent to the inner wall of the cylinder head A3; and in spacedrelation to the rear of the port opening Z2 there is another portopening Z3 in the wall of the sleeve L.

Within the piston B I provide a port opening L2, in the wall of thecylinder chamber L', and another port' opening La spaced to the rearthereof, which leads into a duct L4 eX- tending to the opposite end ofthe piston B where 1t turns downward toward the lower wall thereof. Thepiston rod B is provided on its upper side with a longitudinal y grooveB2 from its rear end forward far enough to communicate with the portopening. Z in the sleeve L when the piston is at the end of its forwardstroke, as shown in Fig. 10; on the opposite side of the piston rod Bthere is a short groove or slot Ba yof a length sufficient to bridge theport openings Z2 and Z3 in the sleeve L when the piston is at the end ofits forward stroke, as

shown in Fig. 10.

In operation when steam is admitted to the 4cylinder head A3 and to thecylinder A, and the piston B moves forward to the end of its stroke, asshown in Fig. 10, the contents of the annular chamber Z will be forcedthrough the groove B2 in the piston rod and the port opening Z, into thehead A3, and the steam trapped and compressed in the forward end of thecylinder A, (or fresh steam admitted to move the piston B backward)wil1flow1 into the port Z2 throu h the slot B2, port Z3 and port L2 into t ecavity of the piston B. On the completion of the rearward stroke (seeFig. 9) the sleeve L having reduced the pressure in the chamber Zuncovers the portl openings L3, and the steam within the cavity of thepiston B will flow through lthe duct L* into 'the chamber Z. On theforward movement of the piston the port L3 will be closed by the sleeveL and steam thus trapped in the chamber Z will be compressed and forcedback through the slot B2 and port Z into the forward cylinder head A3.When the piston B is at the forward end of its stroke all of said portopenings are open to the passage of steam therethrough, but, because theport opening La is closed at that' time there is no direct circulationof steam through the piston, but the same is compressed in the pistoncavity.

The time of coincidence of the ports Z2 and Z3 in the sleeve L with theslot B3 in the piston rod, and the port L2 in the piston during thepause of the piston at the end of 4its forward stroke being controlledby the speed of the engine, it is obvious that the amount of steam whichwill be admitted to the interior of the piston B at the end of eachforward stroke will be reduced as the speed of the engine increases,while the 'Capacity of the sleeve L acting in the cylinder L to exhaustthe steam from the interior of the piston, is not reduced.

In Fig. 11, I show a modification in which the short lower slot B3 isextended forward into the front cylinder head A? where it communicateswith the through a valve controlled opening Z,'so that instead of thepiston B receiving steam from the compression space of the cylinder A,it receives steam from the head A2. In this case I provide a valveA K bymeans of which the iow of steam through the opening Z4 may be restrictedas desired.

In both of the last described forms of mechanism, high pressure steamfrom the cylinder A, or the cylinder head A3 will flow through the portsZ2 and Z3, and L2 interior thereof end of the cylinder.

-end of the piston rod B a stationary rod M extends, which is securedina bushing plug M secured in the rear head A2.' This' ro' M has alongitudinal opening' Mz therethrough, terminating, at -its rear end, ina valve seat upon which a valve M3 is seated.

lThis valve is held in position by means of a stem fm. slidably mountedin an opening in the bushing plug M', said opening beinfr provided witha small lateral opening my,

, through which steam from the cylinder head A2 may enter behind thevalve stein m to maintain the valve M3 closed.

There is provided an openin b* from the chamber B* in the piston ro Binto the interior of the piston B. The p iston B is provided with a portopening N in 'the wall thereof, which, when the piston B is at the endof its lforward stroke coincides with 'a port .N inthe cylinder Acommunicating with the inlet valve seats A at the front The port N isrovided with a regulating valve N2 (see 1g. 14) adapted to restrict thepassage of steam therethrough.

In operation steam is 'admitted to the cylinder heads A2 and A3 and tothe rear inlet port a, and the piston B moves to the end of its forwardstroke, the rod M acting to reduce the pressure in the hollow piston rodB durin the forward movement of the piston, until the port N in thepiston coincides with the port N in the cylinder A; and the port b4 inthe wall of the piston rod is uncovered by the rod M when the reducedpressure in the cavity 4 in the piston rod will be communicated to thecavity in thepiston B and steam from the forward valve seat A will rushinto the piston cavity; this entry of steam into the hollow pistontaking place during the pause 'of the piston while the engine crank ispassing its dead center, it is obvious that the greater the speed of theengine, the shorter will be the interval of time that the ports Nand Nwill be in coincidence to permit the passage of steam therethrough, andon the return 'of the piston B to the position shown in Fig. 12, the steam`trapped in the cavity B4 in the piston rod will be forced backwardthrou h the longitudinal o ening M2 in the rod LE and past the valve sinto the supply of motor steam in the head A2. Likewise. as the speedofthe engine increases, the

-on packing and lubricants.

M remains the same at eac reciprocation of the enginepiston. Thequantity of steam which will flow through the ports N and N may berestricted by the use of the valve N2.

In the use of steam 4heated pistons in steam engines it has'been foundthat as the speed of the engine increases, the flow of hot steam throu hthe piston is increased with the result t at the piston becomes too hotand is detrimental to the operation of the engine, because of thedeleterious effect This dificulty is entirely Iovercome by my inventionfor the reason that as the steam is only admitted yto the circulatingmechanism at the end of the piston stroke while the engine crank ispassing its dead center by means of coinciding port openings, the flowof steam is but momentary, the piston having to make acomplete'reciprocation between the admissions of steam. The steam in allof the constructions herein shown and described,

-entering a chamber of reduced pressure, is

compressed sufficiently to cause it to flow back into the sup ly ofmotor steam, but as the engine speed) increases and the admission ofsteam grows consequently less in uantity, it may be possible that steamfrom t eengine piston may not be ejected there from at each backwardmovement of the piston, as it may' require several backward strokes ofthe piston to build up sufficient pressure therein to overcome thepressure inthe steam supply. This admission of steam maybe restricted byvalves as herein` before described,` if it is found that the pistonbecomes overheated.

From` the foregoing description of the construction and operation of theseveral forms of mechanism adapted to embody my invention, it will beobvious to those skilled in theart, that I am enabled, thereby, to heatthe end walls of an engine piston as may be desired, by introducing aportion of the engines supply of steam into the engine piston andconveying it back into said supply of steam without substantial waste ofsteam. v

Having thus fully shown and described suitable mechanism for embodyingmy invention so that the same may be utilized by others, I do not desireto be limited to the exact mechanism shown and described, as manyalterations and modifications can be made therein without departing fromthe scope of my invention. Therefore what I claim as new and desire tosecure by Letters Patent is 1. The combination in a steam engine, of ahollow piston, circulating mechanism including a cylinder and piston incommunication with said hollow piston adapted to `quantity ofsteaiumtering the piston cavity lis necessarily decreased while theexhausting .cagacity of the rod receive steam and cause it to circulatethrough said .hollow piston, said cylinder having a steam inlet portadapted to be uncovered by the piston therein at the end of one strokeof the engine piston to permit steam to flow into said cylinder; meansto regulate theflow of steam through said inlet port during the time itis uncovered; and means to convey steam away from said circulatingmechanism, substantially as set forth.

2. The combination in a steam engine of a hollow piston, circulatingmechanism including a cylinder secured on the head of the enginecylinder, and a hollow tail-rod extending rearwardly from said hollowpiston, said cylinder and hollow-tail-rod being in communication withsaid hollow piston and adapted to receive steam and cause it tocirculate through said hollow piston;

said cylinder having a steam inlet port adapted to be uncovered by thehollow tailrod at the end of one stroke of the hollow piston to permitsteam toflow into said cylinder, and means to convey steam away fromsaid circulating mechanism, substantially as set forth.

3. The combination in a steam engine of a hollow piston, steamcirculating mechanism including a tail-rod casing having a steam inletport, a hollow tail-rod extending from the hollow piston into saidcasing and adapted to control said steam inlet port, said hollowtail-rod being in communication with the cavity in said hollow piston, aconcentric tube within said hollow tail-rod also having communicationwith the cavity in said hollow piston, means to close the rear end ofsaid hollow tail-rod, a checkvalve to control the flow of steam withinsaid concentric tube, and means to convey steam away from saidcirculating mechanism, substantially as set forth.

4. The combination in a steam engine of a hollow piston, circulatingmechanism including a cylinder and piston in communication with saidhollow piston adapted to receive steam and cause it to circulatetherethrough, said cylinder having a steam inlet port adaptedto beuncovered by the piston therein at the end of one stroke of the enginepiston to permit steam to flow from the supply of engine steam into saidcylinder and means to receive steam from saidA circulating mechanism andconvey it back into the supply of engine steam, substantially as setforth.

5.v The combination in a steam engine :of an engine cylinder, a hollowsteam receiving head thcreoma hollow piston in said cylinder, a hollowtail-rod extending from said piston rearwardly through said cylinderhead, the interior of said piston being in communication with the hollowtail-rod, a port opening in the wall of said hollow tail-rod outside ofsaid cylinder head, a tube concentrically arranged within said tailrodand also being in communication with the interior of said piston, meansto close the rear end of said tail-rod around said tube therein, acasing secured on said cylinder head, a duct in said casingcommunieating with the interior of said cylinder head, a port openingfrom said duct to the interior of said casing, the opening and closingof said last mentioned port opening being controlled by said tail-rod sothat steam is admitted into said casing from said duct at thetermination of the forward stroke of the piston, a non-return valve inthe rear end of said tail-rod to insure a circulation of steam from therear end of said casing through said concentric tube and piston and outthrough the port open-f' ing in said tail-rod, substantially asdescribed. j

6. The combination in a steam engine of a cylinder, a hollow steamreceiving cylinder head thereon, a hollow piston in said cylinder, ahollow tail-rod extending rearwardly through said cylinder head andhaving a port opening in the wall thereof outside of said cylinder head,the piston cavity being in communication with the bore of said tail-rod,a tube concentrically arranged within said tail-rod-being also incommunication with the cavity in said piston, means to close the spacebetween the rear ends of said tail-rod and said tube, a non-return valvecontrolling the entrance of steam into said tube, a casing secured onsaid cylinder head and inclosing said tail-rod, a bushing arranged inthe intermediate portion of said casing around said tail-rod, whichbushing divides the interior of said casing into front and rearchambers` the front chamber being in communication with the interior ofsaid cylinder head, a port opening in said bushing, a duct in saidcasing communicating with the interior of said cylinder head and withthe port opening in said bushing, the opening and closing of the portopenings in said bushing and said tail-rod being controlled by saidtail-rod and said bushing, substantially as described.

In testimony whereof I aiiix my signature in presence of two witnesses.

FRANK L. O. lVADSlVORTH.

Witnesses:

C. A. L. MAssm, WILLARD H. HARTING.

